1. Technical Field of the Invention
The invention is related to the technical field of sonar scanning and more particularly to sonar emitters and towfish.
2. Description of Prior Art
Conventional side-scanning towfish are constructed of stainless steel cylinders which house transducers and electronics. Aluminum or steel stabilizing fins are typically attached to these cylinders along with a towing harness connection and a nose section. A variety of shortcomings arise in this conventional design. The stainless steel cylinders are expensive and require expensive machining to accommodate components, attach fins, and attach harness points. The assembly is subject to seawater leakage into the inside of the cylinder where sensitive electronic components are located. Prevention of leakage requires extensive effort in sealing the electronic components. The metal structure itself is subject to corrosion wherever dissimilar metals are used. Conventional towfish are usually powered by high-voltage (500-1000 volts) DC on the tow cable. Internal electronics use this DC to provide a higher-voltage decaying sinusoid produced by a capacitive-discharge impulse circuit. Peak-to-peak voltages on the order of 4000 volts are produced, but the resultant sound pulse (a decaying sinusoid with fast attack and slow decay) is not ideal for broad-band imaging purposes.